Allowance for Loan Losses - Internal Risk Rating Grades (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
INTERNAL RISK RATING GRADES
Loan Receivables	$ 405,682	$ 161,033
Pass
INTERNAL RISK RATING GRADES
Loan Receivables	370,828	135,703
Watch
INTERNAL RISK RATING GRADES
Loan Receivables	25,953	18,522
Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	833	2,030
Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	8,068	4,778
Construction, Land and Land Development
INTERNAL RISK RATING GRADES
Loan Receivables	57,891	39,818
Construction, Land and Land Development | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	46,344	32,009
Construction, Land and Land Development | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	7,958	5,795
Construction, Land and Land Development | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	270	180
Construction, Land and Land Development | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	3,319	1,834
Farmland
INTERNAL RISK RATING GRADES
Loan Receivables	966	1,023
Farmland | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	966	1,023
Commercial Mortgages (Non-Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	80,240	35,343
Commercial Mortgages (Non-Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	75,168	30,639
Commercial Mortgages (Non-Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	4,345	4,184
Commercial Mortgages (Non-Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	269	272
Commercial Mortgages (Non-Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	458	248
Commercial Mortgages (Owner Occupied)
INTERNAL RISK RATING GRADES
Loan Receivables	73,981	41,825
Commercial Mortgages (Owner Occupied) | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	60,261	31,191
Commercial Mortgages (Owner Occupied) | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	11,058	6,652
Commercial Mortgages (Owner Occupied) | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	254	1,453
Commercial Mortgages (Owner Occupied) | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	2,408	2,529
Commercial and Industrial
INTERNAL RISK RATING GRADES
Loan Receivables	85,939	43,024
Commercial and Industrial | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	84,483	40,841
Commercial and Industrial | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	1,230	1,891
Commercial and Industrial | Special Mention
INTERNAL RISK RATING GRADES
Loan Receivables	40	125
Commercial and Industrial | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	186	$ 167
Residential First Mortgages
INTERNAL RISK RATING GRADES
Loan Receivables	45,718
Residential First Mortgages | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	42,984
Residential First Mortgages | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	1,252
Residential First Mortgages | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	1,482
Residential Revolving and Junior Mortgages
INTERNAL RISK RATING GRADES
Loan Receivables	23,007
Residential Revolving and Junior Mortgages | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	22,924
Residential Revolving and Junior Mortgages | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	33
Residential Revolving and Junior Mortgages | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	50
Consumer and Other Loans
INTERNAL RISK RATING GRADES
Loan Receivables	37,940
Consumer and Other Loans | Pass
INTERNAL RISK RATING GRADES
Loan Receivables	37,698
Consumer and Other Loans | Watch
INTERNAL RISK RATING GRADES
Loan Receivables	77
Consumer and Other Loans | Substandard
INTERNAL RISK RATING GRADES
Loan Receivables	$ 165